In manually operated sealing devices for sealing a cover, typically a die-cut cover that may comprise foil or plastic, for example, onto a container flange, an upper sealing head that pivotally flips open and closed has several advantages over an upper sealing head with purely vertical opening and closing movement, such as a sealing head that slides up and down on vertical shafts, for example.
In particular, a pivotal upper sealing head provides clearer overhead and lateral access to a lower die member when opened, for ease of placement of a container flange to be sealed; displaces the upper die member laterally (i.e., horizontally, transversely, or radially with respect to an axis extending through the respective centers of an upper die member and a lower die member) away from the lower die to make it easier for an operator to avoid accidentally touching an upper die which may be heated; and generally provides a simpler, more compact, and lighter sealing head connection to facilitate portability and efficient use of space, which typically comprises a single pivotal joint instead of a plurality of linear shafts arranged about a perimeter of the die.
However, in existing pivotally actuated container sealers, these advantages come only at the cost of sacrificing seal quality and/or uniformity, as the portion of the upper die member closest to the upper die pivotal axis contacts and begins to apply sealing pressure and, where applicable, heat, to a container cover and flange before other portions of the upper die member. This can result, for example, in undesirable deformation or misalignment of the container cover and flange, and/or a bonded area that extends across less than an entire transverse width of a flange region to be sealed at one or more locations around the flange perimeter.
A need exists for a pivotally actuated container sealing device capable of sealing a cover to a container flange more uniformly and completely than existing pivotally actuated container sealing devices. While pivotal die movement has particular advantages in a manual device as described above, improvements to seal quality, uniformity, and completeness in a pivotally engaging seal die assembly will also benefit automated sealing devices with pivotal die movement. A need also exists for a reliable and efficient container sealing device capable of sealing containers of different diameters and sizes.